We normally go for 8-10 days, have the dining plan and 2 small children. I am a penny pincher by nature, so we don't really spend much OOP. Our last trip we spent $350 in tips, alcoholic beverages, and misc. things like coffee in the am for me.
That total also included 2 $25 giftcards I bought for the kids so they would have their own spending money and could buy what they wanted without going overbudget. It worked great - DD spent her entire amount on candy and small trinkets, and DS saved his until the last day so he could make sure to look around everyday to make sure he got exactly what he wanted.